Non-traditional key signatures

The commonly used \key command sets the keySignature property, in the Staff context.

To create non-standard key signatures, set this property directly. The format of this command is a list:

\set Staff.keySignature =
  #`(((octave . step) . alter) ((octave . step) . alter) ...)

where, for each element in the list, octave specifies the octave (0 being the octave from middle C to the B above), step specifies the note within the octave (0 means C and 6 means B), and alter is ,SHARP ,FLAT ,DOUBLE-SHARP etc. (Note the leading comma.)

Alternatively, for each item in the list, using the more concise format (step . alter) specifies that the same alteration should hold in all octaves.

For microtonal scales where a sharp is not 100 cents, alter refers to the alteration as a proportion of a 200-cent whole tone.

Here is an example of a possible key signature for generating a whole-tone scale: